Field of the Invention
The present invention relates to a probing device for an electronic device and a probing method, and more particularly to a probing device that makes an electrode pad of an electronic device, such as a semiconductor chip (die), MEMS or the like formed on a substrate, such as a semiconductor wafer or the like, in contact with a probe with a predetermined pressure so that an electrical inspection is carried out, and a probing method thereof.
Description of the Related Art
In a semiconductor manufacturing process, various processes are carried out on a thin disc-shaped semiconductor wafer to form a plurality of chips (dies), each having an electronic device. Each chip is inspected for electrical characteristics, and is then individually cut by a dicer and assembled by being secured onto a lead frame or the like.
The above-mentioned inspection for electrical characteristics is executed by utilizing a probe and a tester. As shown in FIG. 3, a wafer W is secured onto a stage 101 that is shiftable in longitudinal directions, and a plurality of probes 102 are installed on a probe card 103 of the wafer W in association with electrode pads (bumps) of an electronic device (not shown).
Upon carrying out electrical inspections, after the position of the probe 102 and the position of the wafer W have been detected, the stage 101 is rotated so as to make the arranging direction of the electrode pads of the chip coincident with the arranging direction of the probes 102. Moreover, after the electrode pads of the chip to be inspected of the wafer W have been moved so as to be located under the probes 102, the stage 101 is raised so that the electrode pads are made in contact with the probes 102.
Each probe 102 exerts a spring characteristic so that by raising the contact point from the tip position of the probe 102, it is made in contact with the electrode pad with a predetermined contact pressure. Moreover, by taking into consideration the inclination between the wafer W and the arrangement surface of the tips of the probes 102 and deviations of the tip positions of the probes 102, in order to positively make the electrode pads and the probes 102 in contact with each other, the electrode pads are raised up to a position higher than the tip positions of the probes 102, that is, the surface of the wafer W is raised by a distance α. This is referred to as “overdrive”, and the movement amount by which the surface of the wafer W is further raised from the tip positions of the detected probes 102, that is, the above-mentioned distance α, is referred to as “overdrive amount” (for example, see Patent Document 1).
Moreover, the electrode pad is formed by using soft aluminum, gold or the like with a thickness (height) of 20 to 100 μm relative to the chip plane (surface of the wafer W), and for example, as shown in FIGS. 4 to 6, is formed into various shapes, such as a semi-spherical shape, a trapezoidal shape, a pommel-horse shape (or an oval shape), or the like.
More specifically, FIGS. 4(a), 4(b) and 4(c) show an electrode pad 104 having a semi-spherical shape, and on its side view shown in FIG. 4(a) and its longitudinal side view shown in FIG. 4(b), the shape is indicated as a semi-spherical shape and in its plan view shown in FIG. 4(c), it is indicated as a round shape.
FIGS. 5(a), 5(b) and 5(c) show an electrode pad 204 having a trapezoidal shape, and on its side view shown in FIG. 5(a) and its longitudinal side view shown in FIG. 5(b), the shape is indicated as a trapezoid with its upper surface (top surface) being flat, and in its plan view shown in FIG. 5(c), it is indicated as a rectangular shape.
FIGS. 6(a), 6(b) and 6(c) show an elongated electrode pad 304 having a pommel-horse shape (or an oval shape), and on its side view shown in FIG. 6(a) and its longitudinal side view shown in FIG. 6(b), its upper surface has a peak shape, and in its plan view shown in FIG. 6(c), it is indicated as an oval shape (elongated circular shape).
In the case when, upon carrying out an inspection for electrical characteristics on an electronic device, the electrode pads 104, 204 and 304 are made in contact with the probes 102 in an overdrive state, the tips of the probes 102 are pressed and embedded into the surfaces of the electrode pads 104, 204 and 304, with the result that needle traces 105 are respectively formed on the surfaces of the electrode pads 104, 204 and 304.
Therefore, in general, as a method for confirming whether or not an appropriate inspection has been executed, with the tips of the probes 102 and the surfaces of the electrode pads 104, 204 and 304 being made in contact with each other, determination is made by carrying out an inspection for the presence or absence of the needle traces 105.
Moreover, conventionally, in the needle trace inspection, light is applied onto the surface of each of the electrode pads 104, 204 and 304 through a microscope, and white shinning portions or black non-reflecting portions are determined as the needle traces 105 depending on gradations of black and white.
[Patent Document 1] Japanese Patent No. 4878919
However, as described above, the surfaces of the electrode pads have shapes, such as a semi-spherical protruding shape (see FIG. 4), a plane shape (see FIG. 5), a semi cylindrical protruding shape (see FIG. 6), or the like. In the method for applying light onto the surfaces of the electrode pads 104, 204 and 304 respectively through microscopes so that white shinning portions or black non-reflecting portions are detected as the needle traces 105 depending on gradations of black and white, the presence or absence of the needle traces 105 is determined in the following manner.
(1) As shown in the electrode pad 104 of FIG. 4, in the case when the surface protrudes to form a semi-spherical shape (or a dome shape), an apex 104a of the electrode pad 104 is raised toward the tip of the probe 102 in the order of FIG. 4(d) and FIG. 4(e), with the result that when a pressing force F is applied onto the apex 104a of each of the electrode pads from the probe 102, a needle trace 105 is formed on the apex 104a of the electrode pad 104, as shown in FIG. 4(e). That is, in the case when the surface of the electrode pad 104 protrudes to form the semi-spherical shape, upon application of light through a microscope, the portion of the needle trace 105 looks white as shown in FIG. 4(f). On the other hand, when the apex 104a of the electrode pad 104 deviates from the tip of the probe 102, and when the edge portion 104b of the electrode pad 104 is raised in the order of FIG. 4(g) and FIG. 4(h), a pressing force F is applied onto the edge portion 104b from the probe 102, and as shown in FIG. 4(i), the edge portion 104b of the electrode pad 104 is pressed onto the tip of the probe 102 so that the needle trace 105 is formed on the edge portion 104a. In this case, there is a height difference between the apex 104a and the edge portion 104b of the electrode pad 104 respectively made in contact with the probe 102, with the result that gradations of black and white become unclear since the focal points of the microscopes are different. Moreover, since the surface of the electrode pad from the apex 104a toward the edge portion 104b is curved, light from the microscope is irregularly reflected, with the result that the detection of the needle trace 105 becomes difficult. Therefore, in the case when an operator visually carries out a needle-trace inspection, since the focal point needs to be adjusted on each of the electrode pads 104, there is a difference between individual persons in precision. Furthermore, since the number of the electrode pads 104 formed on a chip (electronic device) reaches several thousands to several tens of thousands depending on cases, to carry out an inspection one by one causes a problem of a load imposed on the operator.
(2) As shown in the electrode pad 204 having a trapezoidal shape of FIG. 5, in the case when an apex surface 204a forms a flat shape, the flat apex surface 204a of the electrode pad 204 is raised toward the tip of the probe 102 in the order of FIG. 5(d) and FIG. 5(e), with the result that when a pressing force F is applied onto the apex surface 204a thereof from the probe 102, a needle trace 105 is formed on the flat apex surface 204a of the electrode pad 204, as shown in FIG. 5(e). Upon application of light onto the flat apex surface 204a of the electrode pad 204 from a microscope, the portion of the needle trace 105 looks black as shown in FIG. 5(f), with the other portions of the apex surface 204a looking white. On the other hand, when the apex surface 204a of the electrode pad 204 deviates from the tip of the probe 102, and when the edge portion 204b that is tilted in a manner so as to be lowered outward from the apex surface 204a is raised in the order of FIG. 5(g) and FIG. 5(h), with the result that a pressing force F is applied onto the edge portion 204b from the probe 102, as shown in FIG. 5(i), the edge portion 204b of the electrode pad 204 is pressed onto the tip of the probe 102 so that the needle trace 105 is formed on the edge portion 204b. In this case also, there is a height difference between the apex surface 204a and the edge portion 204b of the electrode pad 204 respectively made in contact with the probe 102, with the result that gradations of black and white become unclear since the focal points of the microscopes are different, to cause a difference between individual persons in precision, making it difficult to detect the needle trace 105 with high precision and raising a problem of a load imposed onto the operator.
(3) As shown in the electrode pad 304 having a pommel-horse shape (oval shape) of FIG. 6, in the case when an upper-side surface forms a peak shape, the apex (ridge line) 304a of the electrode pad 304 is raised toward the tip of the probe 102 in the order of FIG. 6(d) and FIG. 6(e), with the result that when a pressing force F is applied onto the apex 304a thereof from the probe 102, a needle trace 105 is formed on the apex 304a of the electrode pad 304, as shown in FIG. 6(e). Upon application of light onto the apex 304a of the electrode pad 304 from a microscope, the portion of the needle trace 105 looks white as shown in FIG. 6(f), with the other plane portion looking black. On the other hand, in the case when an edge portion 304b of the electrode pad 304, which deviates from the apex 304a of the electrode pad 304 relative to the tip of the probe 102 and is also curved to be lowered outward from the apex 304a, is raised in the order of FIG. 6(g) and FIG. 6(h), with the result that a pressing force F is applied onto the edge portion 304b from the probe 102, as shown in FIG. 6(i), the edge portion 304b of the electrode pad 304 is pressed onto the tip of the probe 102 so that a needle trace 105 is formed on the edge portion 304b. In this case also, there is a height difference between the apex 304a and the edge portion 304b of each of the electrode pads 304 respectively made in contact with the probes 102, with the result that gradations of black and white become unclear since the focal points of the microscopes are different, to cause a difference between individual persons in precision. Moreover, since the surface of the electrode pad is curved from the apex 104a toward the edge portion 104b, light from the microscopes is irregularly reflected, making it difficult to detect the needle trace 105 with high precision and raising a problem of a load imposed onto the operator.
In the case of the electrode pad 104 having a semi-spherical shape shown in FIG. 4, as shown in FIGS. 4(d) to 4(f), in the case when the apex 104a of the electrode pad 104 is pressed onto the tip of the probe 102 so that the needle trace 105 is formed, a plane external shape 104c obtained when the electrode pad 104 before an inspection is seen from right above is indicated by FIG. 4(j) and a plane external shape 104c obtained when the electrode pad 104 after the inspection is seen from right above is indicated by FIG. 4(k); therefore, both of these have the same shape before and after the inspection. In contrast, as shown in FIGS. 4(g) to 4(i), in the case when an edge portion 104b of the electrode pad 104 is pressed onto the tip of the probe 102 so that a needle trace 105 is formed on the edge portion 104b, a plane external shape 104c obtained when the electrode pad 104 after the inspection is seen from right above is indicated by FIG. 4(l); thus, a swelled portion protruding outward from the outer periphery, that is, a protruding portion 104d, is formed relative to the plane external shape 104c, when the electrode pad 104 is viewed from right above before the inspection so that different shapes are formed before and after the inspection. The protruding portion 104d is a portion which corresponds to one portion of the electrode pad 104 that is squashed and swelled outward when the edge portion 104b of the electrode pad 104 is pressed onto the tip of the probe 102. Therefore, it is also possible to confirm whether or not the electrode pad 104 is made in contact with the probe 102 with a predetermined pressure so that an appropriate inspection is carried out, depending on whether or not one portion of the electrode pad 104 is squashed to be deformed outward so that the protruding portion 104d is formed at a portion other than the needle trace 105.
In the case of the electrode pad 204 having a trapezoidal shape of FIG. 5, as shown from FIGS. 5(d) to 5(f), in the case when the apex surface 204a of the electrode pad 204 is pressed onto the tip of the probe 102 so that a needle trace 105 is formed, a plane external shape 204c obtained when the electrode pad 204 before an inspection is seen from right above is indicated by FIG. 5(j) and a plane external shape 204c obtained when the electrode pad 204 after the inspection is seen from right above is indicated by FIG. 5(k); therefore, both of these have the same shape before and after the inspection. In contrast, as shown in FIGS. 5(g) to 5(i), in the case when an edge portion 204b of the electrode pad 204 is pressed onto the tip of the probe 102 so that a needle trace 105 is formed on the edge portion 204b, a plane external shape 204c obtained when the electrode pad 204 after the inspection is seen from right above is indicated by FIG. 5(l); thus, a swelled portion protruding outward from the outer periphery, that is, a protruding portion 204d, is formed relative to the plane external shape 204c, when the electrode pad 204 before an inspection is viewed from right above so that different shapes are formed before and after the inspection. The protruding portion 204d is a portion which corresponds to one portion of the electrode pad 204 that is squashed and swelled outward when the edge portion 204b of the electrode pad 204 is pressed onto the tip of the probe 102. Therefore, in this case also, it is also possible to confirm whether or not the electrode pad 204 is made in contact with the probe 102 with a predetermined pressure so that an appropriate inspection is carried out, depending on whether or not one portion of the electrode pad 204 is squashed to be deformed outward so that the protruding portion 204d is formed at a portion other than the needle trace 105.
In the case of the electrode pad 304 having a pommel-horse shape (or an elongated circular shape) of FIG. 6, as shown in FIGS. 6(d) to 6(f), in the case when the apex 304a of the electrode pad 304 is pressed onto the tip of the probe 102 so that a needle trace 105 is formed, a plane external shape 304c obtained when the electrode pad 304 before the inspection is viewed from right above is indicated by FIG. 6(j) and a plane external shape 304c obtained when the electrode pad 304 after the inspection is viewed from right above is indicated by FIG. 6(k); therefore, both of these have the same shape before and after the inspection. In contrast, as shown in FIGS. 6(g) to 6(i), in the case when the edge portion 304b of the electrode pad 304 is pressed onto the tip of the probe 102 so that the needle trace 105 is formed on the edge portion 304b, a plane external shape 304c obtained when the electrode pad 304 after the inspection is viewed from right above is indicated by FIG. 6(l); thus, a swelled portion protruding outward from the outer periphery, that is, a protruding portion 304d, is formed relative to the plane external shape 304c, when the electrode pad 304 is viewed from right above so that different shapes are formed before and after the inspection. The protruding portion 304d is a portion which corresponds to one portion of the electrode pad 304 that is squashed and swelled outward when the edge portion 304b of the electrode pad 304 is pressed onto the tip of the probe 102. Therefore, in this case also, it is also possible to confirm whether or not the electrode pad 304 is made in contact with the probe 102 with a predetermined pressure so that an appropriate inspection is carried out, depending on whether or not one portion of the electrode pad 304 is squashed to be deformed outward so that the protruding portion 304d is formed at a portion other than the needle trace 105.
Therefore, technical problems are raised when an attempt is made to provide a probing device and a probing method for an electronic device which make it possible to recognize whether or not an electrical inspection has been appropriately carried out, with the electrode pad being made in contact with a probe with a predetermined pressure, by utilizing a change in an external shape formed on the electrode pad when the probe and the electrode pad are pressed onto each other, and the object of the present invention is to solve these problems.